Microwave antennas have been designed to treat various medical conditions by microwave energy delivery. Such microwave antennas may be used for ablating or otherwise modifying tissue. For example, microwave antennas have been used for ablating cardiac tissue to treat cardiac arrhythmias. In several applications of microwave antennas including cardiac ablations, it is very advantageous to have an additional modality located on the microwave antenna. For example, it is very advantageous to have one or more electrophysiological mapping electrodes located on or near a microwave antenna used for cardiac ablation. Such a design enables the user to ablate cardiac tissue using the microwave antenna and also detect electrophysiological signals using the mapping electrodes. Simply adding an additional modality such as mapping electrodes and the conductive wires over a microwave antenna may create a microwave antenna that is unsuitable for clinical use. The additional modality and the conductive wires may absorb microwave energy and become hot. This in turn may causes problems such as burning or charring of tissue, creation of undesirable blood clots and adherence of the microwave antenna to tissue. In addition, additional modality and the conductive wires connected to the additional modality may change the shape of the microwave field emitted by the microwave antenna. This in turn may create a shaped microwave field that is no longer clinically useful. Such a shaped microwave field may also create additional safety issues by undesired microwave energy delivery to healthy tissue. The microwave field may also affect the functioning of the additional modality. Thus, there is a need for microwave antennas that comprise such additional modality such that the safety and the performance of such antennas is not compromised.
Medical diagnostic and surgical procedures generally require that physicians perform many increasingly complex functions within the body. In many of these procedures, the physicians must properly access tissue locations and precisely orient a medical component to perform a diagnostic or surgical procedure. In an ever increasing number of modern surgical procedures, elongate devices are introduced into the target tissue through surgically created access openings or natural openings in the body. Physicians deliberately keep such access openings small to minimize the trauma and the healing burden on the patient. For example, in many catheter-based cardiac procedures, a physician will access internal cardiac tissue by navigating a device through the vasculature until the device can engage the cardiac tissue (e.g. a chamber of the heart). In another example, a physician may create an opening (or rely upon a natural body opening) to access organs and tissues requiring a medical procedure. Traditionally, the desire to minimize trauma to the patient often comes at the expense of the maneuverability of the medical component when compared to a similar open surgical procedure. For instance, a physician working with his hands and having full access to a target site such as during an open surgery has much greater freedom to manipulate one or more medical devices to access target tissue and position and orient the medical devices as needed to perform many functions. Yet, such freedom is lost during minimally invasive procedures and in some open surgical procedures where the physician's access to the target site is limited due to obstructing tissue or organs (such as accessing the interior of an organ through a wall of the organ).
Many conventional approaches attempt to overcome these limitations on maneuverability by providing a device with a steerable distal end. However, these existing devices are unable to provide the optimal amount of articulation and/or manipulation needed within the body, especially when the procedure is performed under fluoroscopy.
To illustrate this point, consider the situation in an open surgical procedure, where a physician is able to use one or both arms to directly manipulate a treatment device onto or along a body structure. The numerous degrees of freedom offered by a single arm (including the hand, the wrist and fingers) enables satisfactory placement of the treatment device. When the physician attempts the same procedure through a limited access (either a smaller incision, use of access ports, intravascularly or even through dissection of other tissues/organs), conventional steerable devices do not provide sufficient maneuverability. For example, catheter-based interventional endocardiac ablations for treating Atrial Fibrillation suffer from shortcomings due to a lack of access to all target regions within the atria. For a successful procedure, it is critical to access specific target regions within the left atrium and create a series of ablations in a specific pattern. Existing steering devices are inadequate in providing this function. This reduces the efficacy of the procedure, increases the procedure times and necessitates the use of very expensive accessory devices such as surgical navigation systems.
In view of the above, there remains a need for a device or system that offers improved positioning of one or more medical device components in various medical procedures. There also remains a need for a device or system that allows a physician the capability to position an appropriate medical component readily and predictably at all desired locations (where the locations may be 2 or 3 dimensional structures) for performing the required procedure such as catheter based cardiac ablation.